How much of a concern is a single rust pit, from one land to the next, on a 50 cal.
Much affect on accuracy?
Take it to the range a couple times and find out.
99.9999% probability - none.
Some bores never shoot well new, and some shoot great - even after they’ve been neglected.
Range time will tell, but if you’re shooting a known accurate load, I wouldn’t expect any difference.
Worst thing with pitting IMHO is the decreasing amount of shots between cleaning - or swabbing the bore.
Best bet: don't let it get rusty in the first place. There was a lot of truth in the old timer's saying "never let the sun set on a dirty bore without cleaning it."
young fella gave me a cva inline thingamajig. bore is the poster bore for a sewer pipe look a like.
the thing shoots lights out even with the ragged bore. shreds cleaning patches and is a kamela harris to clean.
did i mention it shoots wonderfully?